At the start screen where it shows a random neighbor walking around your town and it says press to start, press L+R to activate this code.

Code:
94000130 FCFF0000
D3000000 021E3122
C0000000 00000FFF
DC000000 00000002
F2000000 00000002
82000000 00004013
72000000 0000401B
10000000 0000FFF1
D2000000 00000000
Once you've done that, press L+Up to activate this code.

Code:
94000130 FDBF0000
121e401a 0000501a
d2000000 00000000
Then try to play...